[LLVMdev] SLP vectorizer on AVX feature (original) (raw)

Hal Finkel hfinkel at anl.gov
Wed Jul 1 13:38:59 PDT 2015

----- Original Message -----

From: "Frank Winter" <fwinter at jlab.org> To: "Renato Golin" <renato.golin at linaro.org> Cc: "LLVM Dev" <llvmdev at cs.uiuc.edu> Sent: Wednesday, July 1, 2015 3:33:18 PM Subject: Re: [LLVMdev] SLP vectorizer on AVX feature

On 07/01/2015 04:29 PM, Renato Golin wrote: > On 1 July 2015 at 21:22, Frank Winter <fwinter at jlab.org> wrote: >> there were two follow-up emails. > I only got one... weird... > > >> The issue is solved. The SLP vectorizer has >> a magic number built into the code which determines the max. >> vector length >> to search for. That was set to 128 bits. Increasing it to 256 bits >> solved >> the issue. > That looks like a simple fix. Is it upstream yet? :) That's not up to me. There were concerns raised about an increased compile time. https://llvm.org/bugs/showbug.cgi?id=17170#c8

The first step, likely, is to transform this bound into a command-line option for ease of benchmarking. I think that a patch that does that (along with a test case) would be nice.

-Hal

Frank > > >> For inconsistency reasons it must be '--debug-only=SLP' and the >> output can >> be found in one of the follow-up emails. > Of course. Maybe we should mean "vectorize" as all of them? Anyway, > that's unrelated. > > cheers, > --renato

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-- Hal Finkel Assistant Computational Scientist Leadership Computing Facility Argonne National Laboratory

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